In my above mentioned U.S. Pat. Nos. 5,061,219 and 5,137,486 (hereinafter referred to as my first patents), I disclose a novel and improved form of construction toy comprising connector elements, and strut elements adapted to be removably engaged with the connector elements to form composite structures. In the first patents, certain forms of connector elements are described, which incorporate a variety of unique and advantageous features greatly enhancing performance while enabling the elements to be mass-produced at very low cost by injection molding techniques. Common to both of the first patents is a structure in which the connector elements are formed with at least one open-ended recess for receiving and retaining a strut element by its end. Each recess is formed with an inner end wall and a pair of spaced-apart side walls. The side walls are formed with concave grooves extending longitudinally from the open end of the recess, toward the inner end wall, but terminating short of the end wall. A strut element, having a generally cylindrical envelope, is arranged to be received within said concave grooves and thus aligned along the axis of the recess. Cooperating rib and groove means are provided on the recess walls and on the end of the strut element such that, when the strut element is forced laterally into the open side of a recess, it is both gripped and aligned by the grooved side walls of the recess, and locked against axial motion by the cooperating rib and groove arrangement. The described structural arrangement is, in large part, employed throughout the inventions described hereinafter, being utilized to form connector elements of a wide variety of geometric configurations. The arrangement is such to provide an overall construction toy system which accommodates virtually unlimited possibilities for the design and construction of formations and structures, both static and dynamic in character.
In part, the present invention is directed to the construction of connector elements having from one to a substantial plurality of socket-forming recesses for the reception of rod-like strut elements. In a particularly advantageous embodiment of the construction system, connector elements having a plurality of socket-forming recesses are arranged so that the individual recesses are angularly spaced by 45.degree., or multiples of 45.degree., although this particular angular arrangement is not conceptually critical. Thus, in a typical construction toy system, connector elements typically may be provided with one to eight socket-forming recesses arrayed about a central axis.
In certain cases, and as particularly described in my U.S. Pat. No. 5,137,486, one of the recess positions of a connector element may be especially designed for cooperative assembly with a second connector element having a similar recess position, providing for an assembly of connector elements with arrays of socket-forming recesses disposed in more than one plane. An assembly of such connector elements can be provided which accommodates the mounting of strut elements extending in four planar directions from a central axis. According to the disclosure of the present application, modified forms of such connector element assemblies are provided in which strut elements extend in three planar directions (forming a Tee-shaped joint) or in two planar directions (forming a right angular corner joint).
In accordance with another aspect of the present invention, the design and construction of the socket-forming recesses, on the one hand, and the ends of the strut elements, on the other hand, is such that the cooperative action of the rib and groove means serves to yieldably urge the strut elements axially into tight end face contact with the end wall of the recess. This provides for a significant degree of additional stability in the connection between the strut and connector.
To particular advantage, the construction toy system of the present invention includes a series of struts of graduated lengths, graduated in accordance with a predetermined formula such that when two struts of a given length in a series are joined with connector elements to form a right angularly related structure, the strut of the next larger length in the series is of an appropriate length to be joined in the assembly along the hypotenuse of the triangular structure. In this manner, a large structural assembly may be formed utilizing rigid triangular structural subassemblies of various different sizes for maximum strength and rigidity.
In the system of the invention, in which a series of strut elements of graduated lengths is provided according to the before mentioned principle, a structure consisting of a pair of like strut elements of a given length in the series, mounted on opposite sides of a connector element so as to be coaxial, are equal in length to the length of a strut element two sizes larger in the series. This arrangement provides for an extraordinary degree of flexibility in the arrangement of structural parts in any assembly.
A significant aspect of the foregoing geometric relationship is the fact that the strut elements can be assembled with the connector elements by lateral snap-in assembly, so that the center-to-center distance of a pair of connector elements does not have to be enlarged in order to receive a strut element. This enables a structure to be easily added to and/or modified even after it has reached a stage of substantial rigidity.
To advantage, the rod-like strut elements of the new construction toy system are provided throughout most of their length with a grooved cross section, preferably an "X-shaped" cross section. The longitudinally extending grooves formed by the "X-shaped" cross section of the rods enables the rods to be inserted crosswise into the open ends of socket-forming recess of the connector elements and pressed into alignment with opposed rib-like projections provided on the gripping arms. The rib-like projections are caused to be snap fitted into opposed longitudinally extending grooves in a strut element, to tightly grip the strut element in a crosswise orientation in the connecting element. This provides for an additional dimension in construction possibilities.
Among the structural possibilities enabled by the last mentioned feature of crosswise gripping of structural elements is the assembly of articulated belt-like structures, which can be incorporated into dynamically operated toy structures, such as bulldozers, tanks, conveyor belts and the like, and also static structures such as catenary suspension elements. To this end, one of the forms of connector elements provided by the invention is an element having a single socket-forming recess at one end, and a cylindrical hub section at the opposite end. As will be described in greater detail hereinafter, a belt-like tread or other structure can be assembled from such elements by connecting a series of single unit connector elements in laterally spaced relation with a common, crosswise gripped strut element. The hub portions of all of the connector elements are aligned and receive a second rod-like structural element. To the second rod-like structural element are mounted a second series of side-by-side connector elements, gripping the strut element in crosswise fashion and forming an articulated joint. This assembly may be repeated any number of times, to provide either an endless belt or track, or one of finite length, as dictated by the requirements of the structure being assembled.
In general, connector elements utilized in the construction toy system of the invention are provided with central hub openings to closely but movably receive the strut elements for free rotation. For many dynamic structures, a driving relationship between a strut element, functioning as an axle, and an associated connector element may be desired. To this end, the construction toy system of the invention incorporates a drive element comprising a socket-forming recess of the type described, which is intended for the crosswise reception of a strut element functioning as an axle for an adjacent connector element. The connector elements advantageously are of an open construction, formed with a central hub cylinder forming a bearing, a plurality of spoke-like webs extending radially outward from the hub cylinder and a radial array of socket structures. The drive element according to the invention is formed with a laterally extending drive pin arranged to be received between adjacent spoke-like webs of a freely rotatable connector element, in order to cause the connector element to be locked in rigid, driving relation to the strut on which it is supported. If desired, a pair of drive elements may be attached to the strut element on opposite sides of an otherwise rotatable connector element, thus functioning to lock the connector element in a given position axially, and also to provide for a rotary driving relationship between the connector and the strut.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment of the invention and to the accompanying drawings.